Our research objective is to pursue our investigations of leukemia and cancer chemotherapy through participation in Children's Cancer Study Group A. This organization, composed of a number of cooperative pediatric and cancer institutions, is involved with protocol drug studies of pediatric malignancy, as formulated by the members of the group. The investigations include the treatment of acute childhood leukemia in various stages and prophylactic and therapeutic trials of agents in solid tumors of the young in conjunction with surgery and x- ray therapy. Trials of immunotherapy in conjunction with chemotherapy in leukemia are to be conducted. Data on the natural history and the survival are collected on an ongoing basis. Statistical supervision is maintained in all of the protocol studies and in most cases these studies are randomized to prevent bias.